1. Field of the Invention
The present invention relates to a switching regulator, and more particularly, to a switching regulator capable of turning off a lower gate switch completely during an activation period, to decrease an inductor current rapidly by a conduction of a body diode of the lower gate switch when the lower gate switch is turned off, so as to smooth the inductor current and an output voltage.
2. Description of the Prior Art
Power supply devices play an important role in modern information technology. Among all of the power supply devices, a DC-DC switching regulator is widely utilized, and the major function of the DC-DC switching regulator is to provide a stable output voltage for the electronic components.
In general, a current control DC-DC switching regulator compares a feedback voltage, which is a division voltage of an output voltage, with a reference voltage to generate a voltage error signal, sums a current detection signal related to an inductor current, with a ramp signal to generate a summation signal (for slope compensation), and compares the voltage error signal with the summation signal to control a upper gate switch and a lower gate switch to turn on and off, so as to stabilize the output voltage.
However, during an activation period of the current control DC-DC switching regulator, since the voltage level of the output voltage is smaller, under a situation of the synchronous operations of the upper gate switch and the lower gate switch, after the upper gate switch is turned on and the lower gate switch is turned off and thus the conductor current increases, the conductor current can not effectively decrease when the upper gate switch is turned off and the lower gate switch is turned on. Therefore, the inductor current may continuously increase, such that the output voltage rapidly increases accordingly. Then, when the output voltage reaches a specific voltage, the upper gate switch is turned off continuously and the lower gate switch is turned on continuously. At this moment, the conductor current continuously decreases and the output voltage stays at the specific voltage. As a result, the conductor current and the output voltage are not smooth. Thus, there is a need for improvement of the prior art.